Conventionally, in a case where a plurality of cages are juxtaposed, a group-supervising operation is usually performed. One system of the group-supervising operation is an assignment system. In this system, as soon as a hall call is registered, assignment estimation values are calculated for the respective cages. A cage having the best assignment estimation value is assigned as a cage-to-serve, and only the assigned cage is made to respond to the hall call, thereby intending to enhance the service efficiency of the elevator system and to shorten the wait times of hall calls.
The assignment estimation values in the system for assigning hall calls as stated above are calculated on the basis that, assuming present circumstances to proceed as they are, which of the cages should optimally be assigned. More specifically, on the basis of cage positions and cage directions at present and hall calls and cage calls presently registered, there are obtained predicted arrival times which are predicted values of time periods required for each cage to successively respond to the hall calls and arrive at the halls of the corresponding floors, and continuation time periods which are the time period elapsed since the registrations of the hall calls. Further, the predicted arrival times and the corresponding continuation time periods are added to calculate predicted wait times with regard to all the hall calls presently registered. Then, the sum total of the predicted wait times or the sum total of the squared values of the predicted wait times is set as an assignment estimation value by an assignment estimation value calculation means, and assignment is outputted to the cage whose assignment estimation value is the minimum.
The following are examples of such a conventional system for group-supervising an elevator system:
(A) Cage positions after a predetermined time period are predicted to decide a standby floor and make an unoccupied cage stand by on the standby floor (see Japanese Patent Application Publication No. Hei 7-25491 corresponding to U.S. Pat. No. 5,058,711); and PA1 (B) Assignment and standing by are conducted in accordance with intervals between the respective cages after a predetermined time period (see Japanese Patent Application Publication No. Hei 7-72059 corresponding to U.S. Pat. No. 4,982,817).
However, the conventional systems stated above involve problems.
With the system (A), only the standby operation is taken into consideration, and thus, the system (A) is substantially effective only in off-time.
With the system (B), only the intervals between the respective cages are taken into consideration, and quantitatively servicing the respective floors is not taken into consideration, and thus, the respective floors are serviced unevenly.
The present invention is made to solve the aforementioned problems. An object of the present invention is to provide a group-supervising control system for an elevator which, by making even the time periods until the service is available with regard to the respective floors, can decrease the service unevenness, thereby carrying out efficient group supervision.